I am definitely dispensational in my approach to doctrine. Many things change from one dispensation to another. However, I have stopped short of making salvation in any age be the the result of works--even when presented as faith and works. I have covered this teaching in other places and will not go into depth here. However, Romans chapter four and the statements found there are critical to my reasoning.
Yet, as you point out in Matthew 25, there are passages that create problems with this teaching. I will state that I do not think that the grace of God is as evident in every dispensation and that the connection between faith and works is stronger in many dispensations than it is today. That is, faith produces works. Paul speaks of the "work of faith" (1 Thessalonians 1:3; 2 Thessalonians 1:11). Therefore, the way we recognize faith in another is through their works. But we must understand the order. We work because of our faith. We do not believe because of our works. Therefore, faith is the cause of salvation; not the works. In effect, I believe this has been true even in those dispensations which greatly emphasize the importance of works--like the time of the law and the time of the tribulation. Those who believe do the works that are required, but it is the faith that truly makes the difference.
Now, the teaching of Matthew 25:31-46 is not a place I would take people to teach them salvation by faith alone. But that is not the purpose of this teaching. Its purpose is to show the main difference between the righteous Gentiles and the unrighteous Gentiles during the time of the tribulation. The difference is found in how they treat God's earthly people, the Jews. However, it is not a plan of salvation. If it is, then there are several plans of salvation in tribulation. To be saved in the tribulation, you must:
- Minister to God's people, the Jews (Matthew 25)
- Endure to the end (Matthew 24:13).
- Refuse to take the mark of the beast (Revelation 14:11).
- Keep the commandments (Revelation 14:12).
- Keep the faith of Jesus (Revelation 14:12).
- They cannot be fearful (Revelation 21:8)
- They cannot tell a lie (Revelation 21:9)
- Not add to the words of God (Revelation 22:18).
- Not take away from the words of God (Revelation 22:19).
I can see where people get the idea of works here and I have good friends who take this approach. However, this kind of plan of salvation confuses me. What if someone does not meet a Jewish person during the tribulation? Can they be saved? Which of the commandments will send them to hell? Which will not? This is a most confusing plan of salvation and does not seem to match the statements of the Bible in other places.
Most interpreters have no problems seeing the impossibility of those of us living in the age of grace living up to these standards. However, they teach that it will be possible for those in the tribulation to do so without the level of grace we have today and without the indwelling Spirit of God. They teach that these people will simply be back under law as in the days of the Old Testament. But did the Old Testament saints go to heaven by keeping it? No. When the New Testament Jewish believers tried to put the Gentile believers under the law, Peter told them, "Now therefore why tempt ye God, to put a yoke upon the neck of the disciples, which neither our fathers nor we were able to bear?" (Acts 15:10). Paul spends much energy telling us that no one was ever able to keep the law but Jesus and that salvation was not possible by the keeping of the law.
But keeping the law is only one requirement of many for salvation according to these teachers. I have come to the point where I cannot grasp the concept of anyone in any age going to heaven even partially by their own merits. 1 Corinthians 4:5 says of the time when the Lord will reveal all secrets, "then shall every man have praise of God." I believe that is certainly true of every age.
The approach I have taken is that of association. Generally speaking, those who have truly believed can be identified by their outward actions. Of course, we know that hypocrisy is a great problem at this time. Many pretend to be saved who are not. But what about a time when pretending to be saved would starve you to death or get your head cut off as quickly as really being saved? Would there be hypocrites during such a time? I think not. Only those who truly believed would refuse to take the mark of the beast and worship him--especially when doing so means instant death. Only those who looked to the Lord would feed the hated Jews and give them drink.
Some might agree with me on this point but protest that even without without hypocrites pretending to be believers there would still be true believers who would pretend to be unbelievers. This is evidently a dispensational difference in the tribulation. All true believers are TRUE believers. There are no halfway believers as we seem to be infested with in this age. But does not the fierceness of the times bear this out? We have many halfway believers in America, but how many are to be found in lands under strong persecution? There may be some, but they are much more rare.
I accept that believers during the tribulation will all be of that rare breed. They will be true and faithful to their Lord Jesus Christ. They will refuse the mark of the beast. Yet, the cause of their salvation is still their faith in Jesus Christ. At the end of the tribulation, John "saw the souls of them that were beheaded for the witness of Jesus, and for the word of God, and which had not worshipped the beast, neither his image, neither had received his mark upon their foreheads, or in their hands; and they lived and reigned with Christ a thousand years" (Revelation 20:4). Notice the main reason for which they were beheaded--for the witness of Jesus and for the word of God. We are also told that they had not worshipped the beast or receive his mark. However, that was not their plan of salvation. Rather, it was their practice as the saints of God.
Perhaps I am arguing over technicalities. However, I think that you also have a good point in your question. The righteous "inherit" the kingdom prepared for them from the foundation of the world (Matthew 25:34). We do not earn what we inherit. We work for rewards but our inheritance comes by the death of another. And, as you also note, these righteous are surprised at the significance of their actions of kindness to God's earthly people. It seems that God is emphasizing the effect of their righteousness, but there is still much room for the cause to be their faith in God and in His Son Jesus Christ. The fact that this is not dealt with here does not mean we are being taught a new way of salvation.